Eugbe  feank



UNITED STATES PATENT FFICE EUGEN FRANK, OF ELBERFELD, PRUSSIA, GERMANY.

PRODUCTION OF NEW YELLOW COLORING-MATTER.

slPECIEICATION forming part of Letters Patent N0. 329,639, datedNovember 3, 1885.

Application filed July 29, 1885. Serial No. 172,983. (No specimens.)

To all whom it may concern.-

Beit known that I, EUGEN FRANK, residing at Elberfeld, in the Kingdom ofPrussia and Empire of Germany, have invented a new and usetulImprovement in the Manufacture of Dye'Stuffs or ColoringMatters, ofwhich the following is a specification.

My invention relates to the production of a new yellow dyestuft by theaction of tetrazo- (liphenyl upon oxibenzoic acid, especially salicylicacid.

In carrying out my process practically I proceed as follows: Ten (10)kilos of benzidine sulphate are suspended in a finely-cornminutedcondition in one hundred and fifty liters cold water. To this twenty(20) kilos of muriatic acid of twenty-one degrees Baum are added, andthe azotation is accomplished by means of five (5) kilos sodium nitritedissolved in water, which are slowly added. The benzidine sulphate notsoluble in water dissolves gradually and a honey-yellow solution oftetrazo-diphenyl-chloride appears. If the thus obtained tetrazocombination slowly flows into a solution of five to ten kilos of puresalicylic acid (or either of the two other isomeric oxibenzoic acids) inforty kilos soda hydrate and two hundred and fifty liters water Whilestirring violently, the following combi nation is formed, viz:

. OH /OH CcH4-N=N H C511 COH.iN=N-C6H3 COONa COONa OH OH CeHa-N:NH CGHdCsH4N=N-(AH3 COONa CsOONa +2HH a brown-yellow amorphus precipitate of anoxyazo combination, which forms the abovementioned yellow dye-stuff.After having been allowed to rest for several hours the formedprecipitate is filtered, and I then wash with cold water until thisfiltered precipitate is neutral, (until the filtrate does not turn redlitmus-paper blue.) The paste remaining in the press may be immediatelyused for dyeing and printing. In the dry state it represents a brown-redpowder, which is dit'ficult to dissolve in hot water, but insoluble incold water, and when the hot aqueous solution gets cold, small yellowneedle-shaped crystals are formed of a silk-like luster. Theaqueoussolution of these crystals will turn violet-red by acids and brown byalkali.

Owing to the great difiiculty of dissolving the dry combination, it isbest used as a paste for dyeing.

Uninordanted cotton is dyed afine sulphuryellow color in a boiling soapbath, and is conspicuous for producing shades fast to scouring andsunlight.

I do not herein claim the product described, having made a separateapplication therefor.

WVhat I claim as my invention, and desire to secure by Letters Patent,is

The process of producing the new coloringmatter herein described, whichconsists in the azotation of benzidine sulphate by means of sodiumnitrite, forming tetrazo-diphenyl, and treating it with oxibenzoicacids, (especially salicylic acid.) and finally separating and purifyingthe yellow coloring-matter by filtration and washing, as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

EUGEN FRANK.

WVitnesses:

HERM. MATTHIs, RICHARD LEKEBUSOH.

